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authorAdam Manzanares <adam.manzanares@hgst.com>2016-10-17 11:27:28 -0700
committerTejun Heo <tj@kernel.org>2016-10-19 14:34:35 -0400
commit5dc8b362a2374d007bc0db649b7ab6a79dd32bda (patch)
tree0049fe83ff4a87fa490997eaffc0c79194001bb6 /block
parent2facc6dacc64f14efc6fb81e2019f48e992166e2 (diff)
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block: Add iocontext priority to request
Patch adds an association between iocontext ioprio and the ioprio of a request. This is done to enable request based drivers the ability to act on priority information stored in the request. An example being ATA devices that support command priorities. If the ATA driver discovers that the device supports command priorities and the request has valid priority information indicating the request is high priority, then a high priority command can be sent to the device. This should improve tail latencies for high priority IO on any device that queues requests internally and can make use of the priority information stored in the request. The ioprio of the request is set in blk_rq_set_prio which takes the request and the ioc as arguments. If the ioc is valid in blk_rq_set_prio then the iopriority of the request is set as the iopriority of the ioc. In init_request_from_bio a check is made to see if the ioprio of the bio is valid and if so then the request prio comes from the bio. Signed-off-by: Adam Manzananares <adam.manzanares@wdc.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'block')
-rw-r--r--block/blk-core.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index 14d7c0740dc0..361b1b965d89 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1153,6 +1153,7 @@ static struct request *__get_request(struct request_list *rl, int op,
blk_rq_init(q, rq);
blk_rq_set_rl(rq, rl);
+ blk_rq_set_prio(rq, ioc);
req_set_op_attrs(rq, op, op_flags | REQ_ALLOCED);
/* init elvpriv */
@@ -1656,7 +1657,8 @@ void init_request_from_bio(struct request *req, struct bio *bio)
req->errors = 0;
req->__sector = bio->bi_iter.bi_sector;
- req->ioprio = bio_prio(bio);
+ if (ioprio_valid(bio_prio(bio)))
+ req->ioprio = bio_prio(bio);
blk_rq_bio_prep(req->q, req, bio);
}